1. Field of the Invention
The present invention relates to a method of communicating between CPUs in a digital copying machine.
2. Prior Art
In a digital copying machine, recently, as more headway is made in higher-speed processing and multifunctional operation, there has been a rising tendency toward the control of more than one CPUs. In such a copying machine, a communication buffer is generally used for communication between CPU.
Conventionally, with a plurality of communication modes, a communication data region in a communication buffer is determined for each communication mode, and therefore, there is the problem that a buffer having a relatively large capacity is required.
Additionally, in a communication method where new data are automatically transmitted when there is some change of data in a communication buffer, it is necessary for CPUs to retrieve all the regions of the communication buffer, and therefore, a required communication period becomes longer as the communication buffer has a larger capacity.